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  <title>Document</title>
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<body>
  <script>
    const arr = [
      { id: 1, name: '西瓜', state: true, price: 10, count: 1 },
      { id: 2, name: '榴莲', state: false, price: 80, count: 2 },
      { id: 3, name: '草莓', state: true, price: 20, count: 3 },
    ]

    // 需求：把购物车数组中，已勾选的水果，总价累加起来！
    /* let amt = 0 // 总价
        arr.filter(item => item.state).forEach(item => {
          amt += item.price * item.count
        })
    
        console.log(amt) */

    // arr.filter(item => item.state).reduce((累加的结果, 当前循环项) => { }, 初始值)
    const result = arr.filter(item => item.state).reduce((amt, item) => amt += item.price * item.count, 0)

    console.log(result)
  </script>
</body>

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